Development of a dry fabric cleaner for miniature parallel optical interface PRIZM LightTurn connector March 7, 2011 Toshiaki Satake, Brian Teague, Jillcha Wakjira, Alan Ugolini and Darrell Childers US Conec 1
Over view of this talk 1. Back ground 1.1 PRIZM LightTurn connector and applications 1.2 Detailed structure of PRIZM LightTurn connector 2. Cleaner requirements and problems 2.1 Requirements 2.2 Traditional cleaner problems 3. New cleaner development 3.1 New cleaner concept 3.2 Experimental set up 3.3 Dust cleaning condition 3.4 Oil cleaning condition 3.5 PRIZM LightTurn connector with dust and oil mixture 4. Discussion and proposal 5. Conclusions 2
1. Back ground 1.1 PRIZM LightTurn connector and applications The PRIZM LightTurn connector is designed to increase the optical T/R module density on circuit boards. The PRIZM ferrule turns optical beams in a 90 direction using a total internal reflection (TIR) lens on the back side of the ferrule. The ferrule was developed to enable users to improve fiber routing by connection directly to the card edge. The PRIZM LightTurn uses a cover for latching to the T/R module and to reduce the likelihood of accidental contamination. Fig.1 PRIZM LightTurn ferrule, ferrule + cover and a high density installation 3
1. Back ground 1.2 Detailed structure of PRIZM LightTurn connector The PRIZM LightTurn ferrule is made of a transparent material and does not contain any mineral fillers. The material selected can be easily scratched. The optical I/O port is surrounded with a wall of 30 microns. It is necessary to clean the bottom of the trench and the walls of the optical I/O port. Reflective Lens Fiber Cover I/O port is recessed and surrounded with a wall Actual ferrule is clear Optical beam path Wall of 30 microns Fig. 2 Detailed structure of PRIZM LightTurn connector Molded Guide pins align to module interface 4
2. Cleaner requirements and problems 2.1 Requirements (1) Dry cleaning without any solvent. (2) The dry cleaning cloth must be flexible so that it can make proper contact with the bottom and walls of the optical I/O port. (3) To avoid creation of scratches by dust on the I/O port, a soft cleaning cloth and low cleaning pressure is necessary. (4) The targeted dirt to be cleaned is Arizona road dust, skin oil and the residue of IPA. (5) The cleaning process should be simple, consistent and take less than 3 seconds. The process should be comparable to current cleaning tools such as the OPTIPOP R cassette cleaning tool. These requirements are important for efficient equipment assembly works with PRIZM LightTurn connectors on to PCBs and those inspections. 5
2. Cleaner requirements and problems 2.2 Traditional cleaner problems OPTIPOP Reel cleaners Designed for SC/MU/MT connector cleaning for glass optical fiber endfaces in ceramic or hard plastic ferrules. The Cleaning tape fabric is thin and hard. It is difficult to sweep the corner of the trench in the PRIZM LightTurn connector window. The ferrule is easily scratched by the dust during wipe. Solvent based cleaners Designed for automatic cleaning of simplex connectors. The cleaning solvent can penetrate into the small spaces and may reach the back side of the connector. Because PRIZM LightTurn connector has TIR lens any residue from the solvent must be avoided. Fig. 3 Traditional cleaning tape 6
3. New cleaner development 3.1 New cleaner concept Cleaning target Large dust can be blown out using a blast of air. This cleaner targets the fine dust particulates in the I/O port. Nano-fiber brushed fiber concept The soft fibers of the brushed fabric can sweep and trap the dust particulates and oil residues are captured and lifted away by the nano fibers. The soft material conforms to the shape of the I/O port with a minimal amount of pressure. The cleaning tape width is the same as the separation of two guide pins of PRIZM LightTurn connector. Possible cleaning area is between the guide pins and the center trench of I/O surface. We believe the dirt on guide pin is very small and even with a small dirt the connector can be aligned without any major problems because the dirt only increases the separation between I/O surface and the optical devices. 7
3. New cleaner development 3.2 Experimental set up The minimum pressure to wipe off dust, the minimum pressure to cause scratches, and the minimum pressure to wipe off oil were examined with the test plate shown in the upper right of Fig. 4. The plate is made of the same material as the PRIZM LightTurn connector. Micro meter for pressure setting Up/down stage L angle metal Push-pull gauge Wiping direction Test plate (sectioned in six) Cleaning cloth tape Pressure head Rubber pad Test sample connector or plate Stage movement direction for cleaning Horizontal stage Base Fig. 4 62mm 13mm Cleaning test set up 8
3. New cleaner development 3.3 Dust cleaning condition Arizona road dust on the test plate was wiped with a brushed fabric with 0.7 microns diameter fibers. Fig. 5 shows a dust particle trapped in the fibers of the fabric. A 1.4 [mg] amount of dust was spread on the test plate shown in Fig. 6-1 (Dust density is 1.74x10-3 [mg/mm 2 ]). The dust was cleaned with a small pressure of 1.8 [g/mm 2 ] without scratch creation and the new scratches appeared for more than 7.2 [g/mm 2 ] for the tested fabric. 10 mm Fig. 5 Nano-fiber Fabric. Fig. 6-1 Before clean Fig. 6-2 1.8 [g/mm 2 ] Fig. 6-3 5.4 [g/mm2] Fig. 6-4 7.2 [g/mm2] Original scratches Scratches caused by dusts. No scratch. No scratch. Some scratches. 9
3. New cleaner development 3.4 Finger oil cleaning condition Skin oil contamination on the test plate were cleaned with different cleaning pressures as shown in Fig. 7-1 to 7-4. Each picture has a cleaned half on left side and a not cleaned half on right side. With the cleaning pressure of over than 3.6 [g/mm2], the skin oil dirt was wiped off perfectly. Fig. 7-1 1.8[g/mm 2 ] After, Before Fig. 7-2 3.6[g/mm2] After, Before Fig. 7-3 7.2[g/mm2] After, Before Fig. 7-4 14 [g/mm2] After, Before Some residue No residue 0.3mm 0.3mm 0.3mm 0.3mm 10
3. New cleaner development 3.5 Cleaning of PRIZM LightTurn connector with oil and dust Skin oil dirt and Arizona road dust on the optical I/O port were wiped with a cleaning pressure of 15 [g/mm 2 ] and the cleaning cloth length of 20 [mm]. It was cleaned beautifully as shown in Fig. 8-3. Scratches in Fig. 8-3 were not created by this experiment. The remaining particles and imperfections are from the original and have less than 0.1 [db] loss. The average insertion loss increase were 0.18 [db] for skin oil and 2.14 [db] for oil and dust. Fig.8-1. With oil Fig.8-2. Dust add. Fig. 8-3 Wiped. Fig. 8 PRIZM LightTurn connector cleaning with skin oil and Arizona road dust Pressure is 15[g/mm 2 ], swipe length is 20[mm]. 11
4. Discussions and proposal Skin oil residue and Arizona road dust wiped away from the optical I/O port using the cloth. The cleaning pressure was 15 [g/mm2] using a 20 [mm] length of the cleaning cloth. The result was beautiful clean of the I/O port. To wipe off dust on the corner on the optical I/O port at low cleaning pressure, brushed fabric cloth with soft thin fibers is suitable and it is necessary to capture dust among the fibers of the cloth. In this examination, dirt of dust and skin oil mixture were cleaned without causing scratches by using brushed fabric with a low cleaning pressure. As a result, dust and oil dirt were cleaned by one cleaning pressure. 12
4. Discussions and proposal PRIZM LightTurn cleaner concept A concept of PRIZM LightTurn cleaner is shown below. It is modified from a traditional reel cleaner OPTIPOP-R. The cleaner uses brushed fabric to wipe off dirt from the recessed optical I/O port by squeezing the cleaner handle to advance the cleaning cloth. Fig. 9 A concept of PRIZM LightTurn cleaner 13
5. Conclusions Dry cleaning methods for the PRIZM LightTurn connector made of plastic material were investigated. Methods to efficiently wipe off Arizona road dust and skin oils on PRIZM LightTurn connector with low cleaning pressure were examined by using brushed fabrics made of nano fibers. As a result of the examination, we propose a concept cleaner for the PRIZM LightTurn connector that can be a modification of OPTIPOP-R cleaner. 14